Historical weather data, all-time temperature records, and monthly climate averages for Islip, NY. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 4th in Islip runs cool, with average highs of 53° and lows near 38° across 62 years of records. It's a coin-flip day for rain — nearly half of all April 4ths have seen precipitation. The range has been wild though, from a 26° freeze in 1972 to a 75° stunner in 2010.
Islip's weather history has some dramatic bookends: a scorching 104° in July 1966 and a brutal -14° in February 1967, just seven months apart. On the wet side, a single August day in 2014 dropped 13.51 inches of rain, and a January 2022 snowstorm buried the area under 23.5 inches.
Summer is the sweet spot, with highs peaking around 82–84° in mid-July before tapering through fall. If you're cold-averse, avoid mid-January, when average highs barely reach 37°. August is the wettest stretch of the year, so pack accordingly if you're planning a late-summer visit.